In-vehicle charger

Abstract

The present invention is an in-vehicle charger for detecting ground faults originating in sections in which alternating current is flowing. This device is an in-vehicle charger ( 100 ) for charging a vehicle-mounted battery, wherein the device is provided with: a bridge rectifier ( 14 ) for converting alternating current supplied from a power source to direct current; a ground fault detecting circuit ( 21 ) for outputting a test voltage when a test current flows in a circuit in the in-vehicle charger ( 100 ) and, based on changes in the test current in response to the presence or absence of a ground fault resistor, for detecting a ground fault in the circuit of the in-vehicle charger ( 100 ); and a controller ( 23 ) for controlling the ground fault sensing circuit ( 21 ) so as to output a test voltage exceeding the forward voltage of a diode provided by the bridge rectifier ( 14 ).

The invention claimed is: 
     
       1. An in-vehicle charging apparatus that charges a battery mounted on a vehicle, the in-vehicle charging apparatus comprising:
 a bridge rectifier that converts an alternating current supplied from a power supply into a direct current; 
 a ground fault detecting circuit that is provided at a side of the bridge rectifier where the direct current obtained by the conversion of the bridge rectifier flows, that outputs first and second test voltages, and that detects a ground fault occurring in the in-vehicle charging apparatus, based on a test current which changes in response to the presence or absence of a ground fault resistance; and 
 a control section that controls the ground fault detecting circuit so that the ground fault detecting circuit outputs the first and second test voltages, 
 wherein: 
 the control section controls the ground fault detecting circuit so that the ground fault detecting circuit outputs respective test voltages of both the first test voltage of a value smaller than the forward voltage of the diode included in the bridge rectifier and the second test voltage of a value larger than the forward voltage of the diode included in the bridge rectifier, 
 the control section determines that a ground fault occurs in a DC interval on the side of the bridge rectifier where the ground fault detecting circuit is present, if the ground fault detecting circuit detects a test current larger than a first predetermined value when the first test voltage is output, and 
 the control section determines that a ground fault occurs in an AC interval on a side of the bridge rectifier which is opposite to the side of the bridge rectifier where the ground fault detecting circuit is present, if the ground fault detecting circuit does not detect the test current larger than the first predetermined value when the first test voltage is output but the ground fault detecting circuit detects a test current larger than second predetermined value when the second test voltage is output. 
 
     
     
       2. The in-vehicle charging apparatus according to  claim 1 , wherein the test voltage is an AC voltage. 
     
     
       3. The in-vehicle charging apparatus according to  claim 1 , further comprising a resonance capacitor that is provided at a side of the bridge rectifier where the alternating current supplied from the power supply of the bridge rectifier flows.